Question: I've just remove my mudguards from my Ti frame and as usual I have put the bolts back into the frame where the thread goes into a tube - for example in the chain-stay bridge and brake bridge.
I used anti-seize on the threads and did not do them up tight.

Should I be doing this?

I do it because it looks a bit neater and I suppose to stop water getting int but I thought that maybe I am just risking ruining my frame if the bolt gets stuck in there.

Thanks

Answer: 
I usually plug the hole with appropriate size hardware. I add a dab of anti-seize compound. My reasoning (other than appearance) is that while the frame is aluminum or carbon the threaded insert is typically steel and there fore subject to rust.
I leave mudguard, waterbottle mount etc. bolts in the frame, with appropriate grease, anti-seize applied. I do this mostly so I can find them when I need to mount the component again.