It didn't "hit" the 52 week high and then not hang on. It spiked to $72.50 SETTING the 52 week high at some point during the trading day. This stock has been setting new 52 week highs all summer long. Really not at all surprisinig that it came back from that level as some share holders obviously chose to take some profit.
The level it closed at ($70.53) is also a 52 week high for a closing as well as a record high for a closing. When a company is on fire like Petm is right now and continually setting new highs on almost a daily basis it is really somewhat suspect to say they "hit the 52 week high and couldn't hold it".