If someone at work, I a senior-ish role to you were doing the following...
Keeps looking at you, staring almost as though he can't take his eyes off you
Always stops to chat when in the office
Checks that you are OK regularly
Fist bumps you regularly
Regularly and subtley invades personal space (in a non creepy way).
Light pretend punches on your upper arm
He looks/ glances at you when in conversation with others
Always complimenting your work
Says things like 'I always have time for you' and 'I really look forward to the days you are in the office'
Always has your back on work related stuff.
Keeps saying you can go to him if you need to vent about anything
...how would you take that....?