Gong through life is learning how to deal with expectations, or perhaps better not to have them at all. Every day is different. Rewarding someone for extra work or spreading around the good will with the crew if a customer chooses to reward you as the boss, I consider a very positive thing whenever possible. In part, I think how you look at it is in the nature of the type of work relationship between boss and employee, is someone like a for that day employee only, or deeper involved? if the longer term someone draws conclusions that they should be getting such whenever similar situations arise with some extra duties or whatever, they need to work out in their brain that life isn't always so simple. There is the day to day you can get picky thing, or the overall situation of an association over time and what all is involved with that, i.e. the give and take. If a worker sees the boss as someone that wants to be fair and offers the overall consideration of trying to look after their interests in a considerate way, imo there is no need to isolate stuff to analyze and get bothered about. People that want to do that, it seems to me to be short sighted. Keeping score can make you crazy, I don't envy people that operate that way.
That someone is going to be expecting something every time, and basing your own behavior on that, strokes me as catering to their restricted mindset. Is someone sometimes borrowing your tools, or taking advantage of your generosity in another way, plus knowing that you were and are there for them if something important should come up, it's all part of the big picture. I also am not naive enough to think that everyone is built that way to have such a concept as the way that they think. Exploitation is a bad thing, it is an uncomfortable feeling to get the impression that someone is doing that to you, and unfair to want to do that to someone else. Definitely care has to be taken, and trust is big in longer term associations and covers a lot of territory. It's an important think to keep too, not get lazy about it.