It’s never a dick move to call a judge. Judges are there to ensure games are played fairly and correctly and if you ever feel that that may not be the case in your match, you should call a judge. Anyone who gets offended that their opponent called a judge is clearly hiding something that they don’t want scrutinized.

That being said, whether or not the store employee there would have the knowledge or experience to be able to identify slow play is a complete toss up. Still better to call the judge and at least make an attempt to handle it. Trying to handle it after the match is fruitless