And then later he'll probably have like Deja Vu and stuff.
Remember, powerful and emotional dreams can take a hold on people for a while. Though no one can remember a whole of one dream, some people may remember lots of minor parts or a few major parts. Ive had these sort of things before....but that usually only happens when there bad dreams (not nightmares but the in-the-middle type ones). So im guessing Serge wouldnt completely forget everything that happened.