Most of the time, these sensations we experience in dreams are just some way for us to get involved and abosrbed into the dream's plot. Many times they're just random occurences, and other times they seem to recur like for me, I always seem to run slow on dreams, even lucids.

I wouldn't worry about it unless it keeps happening. The thing is, if you start believing it's actually a problem, it'll just happen more often. So just tell yourself it was a one-time thing, and hopefully it was!