You're creating an exothermic reaction, this should have been covered in your training, it's a basic issue often made by newbies and those in training. You are either applying the gel too thick or the clients nails are thin which makes them more likely to experience it. Thin nails are often caused by over buffing in preparation stages. Clients do have thin nails naturally sometimes, mine are like paper. If this a new issue on existing clients its probably due to over buffing.
It could be certain pots causing the issue, for instance clear, as you would use this to create the stress point apex and spine so would apply it thicker to build these. It's rarely experienced with white gel when doing french as this is usually applied fairly thin at the free edge.
