Ideally you don't want to create a different grip for certain shots, irrespective of whether they are longer of short chips. You want the same grip throughout ... BUT:

a weaker grip does help to keep the wrists quiet, which is not always a bad thing when you chip. You don't want too much wrist break on pitch & runs or little chip shots ...

Try it, practice with it and if it works for you by helping you pitch & chip more accurately, go with it.