Okay, I'm hoppin' up on my soap box...
That is ssoooo annoying. Why do they do that?!? I think you tipped perfectly, who gets up in the middle of working on a client?!? Wierd.
BTW, any place you can get a mani/pedi for $25 or the like, watch out! 1/2 the time the techs aren't licensed and their tools certainly aren't clean. Two stories:
1: I am a licensed manicurist for 14 years. I took two of those years and went to work at a podiatrist's (foot Dr.) office. The Dr.'s were not thrilled with people getting peds because of all the fungus and infections they saw in their office. Keep in mind they only saw the "peds gone bad" in the office...I would ask those patients where they had their ped and every time it was at one of these "chop shops". If not being cleaned properly, those whirlpool foot baths can be filthy! I don't want to freak you out so much as to make you aware. If you're not sure how they are cleaned, ask! You have the right to know.
2: I once got a client fom a "chop shop". She was sitting having a ped when the state board walked in for their annual inspection. The girl at the front desk announced their arrival. The girl working on my client and about 5 others got up and ran out the back door! These women, obviously, were not licensed. I'm not saying these women aren't good at what they do, I am saying they may not be trained on proper cleanliness techniques. Hense, the annual inspection.
In conclusion,

ask. Ask how the ped stations are cleaned, their tools are sanitized and to see the licenses of their employees. Those licenses should be displayed where you can see them and there should be a picture on every one.
...hoppin' off now.