I'm not a "true" believer in Gap theory especially in the penny stocks but in my review on the subject it happens a lot. If a stock Gaps up on no news then IMO it generally gets filled in the short term, if a stock gaps up on substantial news then these are more likely to never be filled in the short term.
I have successfully traded the gap theory twice in the last two weeks on two different companies.
PIO Price at posting:
3.7¢ Sentiment: Hold Disclosure: Not Held