On a concrete pool with fiberglass panel sides is it possible to get a leak between the seams of the panels and if so is there a recommended product to seal the seams?

Yes it can leak and will if not installed properly. If it does there is a method and product to deal with it. SEKAFLEX is sealent used with both concrete and fiberglass with 100% satisfaction. If was not used with the installation I would be supprised. Take 4" grider with a diamond blade and score the concret where it meets the fiberglass and fill with sekaflex. Done!