When during meditation we forget where we are As far as I understand, awareness is an important concept in buddhism, and an asset to develop through meditation.

During meditation (following vipassana as taught by Goenka), it has happened to me that I forget where I am at that moment. When this question/feeling arises, the answer comes little by little 
being really general at the beginning, and gradually refining to a more detailed description of where I am, like: 
you are in this country, you came to this place, you are in a retreat, your are sitting in this meditation hall, etc. 

My questions are:


Is this feeling expected at any meditation stage ? 
Is this experience maybe pointing out a mistake in the practice ?


Answers with references are strongly appreciated.
Since you are asking from a specific tradition, I can give a pretty specific answer:
Is this feeling expected at any meditation stage ?
Yes, it is expected at the stage of bhaṅga-ñāṇa (knowledge of dissolution).  Though generally available texts don't mention this phenomenon, teacher manuals make reference to it. Here is the general state that leads to this phenomenon:

For at that time each object that is being noticed seems to him to be entirely absent or to have become non-existent. Consequently, at this stage of knowledge, it seems to him as if he were engaged in noticing something which has already become absent or non-existent by having vanished; and the consciousness engaged in noticing appears to have lost contact with the object that is being noticed.
-- Mahasi Sayadaw, Progress of Insight

Is this experience maybe pointing out a mistake in the practice ?
No, but it is common in bhaṅga-ñāṇa to think that your practice is not progressing because of an inability to notice objects clearly (only noticing their disappearance):

It is for that reason that a meditator may here think: &quot;I have lost the insight&quot;; but he should not think so.
-- Ibid.

The reason for losing perception of where you are in bhaṅga-ñāṇa, or the similar observation also common to bhaṅga-ñāṇa of losing perception of the position of the body (i.e. thinking the body or part of the body has disappeared), is because with bhaṅga-ñāṇa the meditator has broken through the illusion of concept into the reality of ultimate existence, no longer putting attention on concepts like &quot;place&quot; or &quot;body&quot;. Since in ultimate reality you aren't anywhere and your body doesn't exist, these concepts have no place in the yogi's mind at that time.