Is it possible the limb was pruned too close to the trunk? Can't tell for sure if the wound is oval (= too close, round is good) from the photo. If so, would certainly talk to the nursery/grower if you purchased it that way; they should know better. Trees have a harder time compartmentalizing the damage from a flush cut and can seep like that for quite some time.

If you don't get a solid answer on GW, could try sending questions and photo to the local TAMU AgriLife folks for their ideas on diagnosis and treatment.

Here is a link that might be useful: Ask an expert (TX-TAMU AgriLife Extension Service)

Or send a photo to the city arborist.

It sounds like it's not something to be overly concerned with. I looked at it this am and it's not "bleeding", so it must be just a sporadic thing.

Would it be of any value to put a dab of pruning seal on there or would that just create more problems?

Probably will fluctuate with trunk temperature and/or the amount of water available to the roots for take-up. If it were my tree, I'd not do anything with sealer at this time of year unless in a neighborhood where oak wilt has been a serious problem. Wounds over 3 or 4 days old are SUPPOSEDLY not susceptible to wilt spores delivered by sap-feeding (nitidulid) beetles. If seeping is due to a poor cut, pruning sealer could further hamper your tree's efforts to isolate the damage. It's young, so should be able to eventually get it done as it grows.

Might reconsider pruning sealer if it's still seeping when the beetles enter their most active period again next February. However, would try white glue or latex paint before resorting to the tar-like sealers.

It sounds like my best bet is to just let it be unless it gets considerably worse.

The cut is only about the size of a pencil eraser and appears to have been done properly.

Luckily, it hasn't done this since I posted, so I'm hoping it was a fluke!