Yes, you should be concerned because the binary will work for you but probably not in all targeted systems.
The 'errors' you are reporting are warnings and not errors. Pyinstaller tells you that it can't find windows CRT. However if the binary works for you:
probably you have the CRT in some place which can not be found by PyInstaller. Check dlls on your system (probably a file search can help). Check PATH environment var and PYTHONPATH.
probably you have some 32bit vs 64bit issue: the python scripts uses a dll from one type while PyInstaller searches for another dll type which you have not... Check it! I saw in your trace that you are using a Windows 7 OS and PyInstaller is searching dlls in system32. Is your OS 64bit and your python version 32bit? This is some kind of dll smell.
To have a sane and good target binary you should ensure to have all dependencies. Do not rely on Windows updates on your target platforms but prefer packing all dependencies in a single distribution.
To ensure a software running in all platforms you should pack a binary for 32bit and one for 64bit. Or at least one for 32bits working also in a 64bit environment.