5 points in two minutes! That's impressive. And not even on the Show page? Hmm, what gives? My post also got 4 points in 1 hour, and didn't get on Show page.
Possibly automatic voting ring detection, e.g. a user having multiple accounts or asking the same friends to upvote. Then some upvotes don't count even though displayed on the website. The user's previous and following submission also got exactly 5 votes within the first 10 minutes, that might be an indication. If in doubt contact the moderators to look at the raw data.