I have a trainer (small boutique gym) who is habitually late & constantly texts, which rarely if ever has anything to do with business. Yes, it bothers me to no end.
The way you handeld the situation was a good thing minus the “look”.
At the same time, if the trainers texting or ipad activity doesn’t bother the client he’s with that’s between the trainer and the client.
If you trainer’s cell/text activity during “your” session bothers and distracts from you getting what you’ve paid for, then in my opinion you have a right to discuss this with him/her off gym floor and even expect a free make-up session(s).
A “Personal” trainer is hired to be attentive to you, your goals and training during your session. Texting, walking away, scoping the gym or parking lot, and or having conversations with others during your session is unprofessional and should be discretely discussed.
Hope my response helped.