I forgot to claim rrsp contributions I made for the first 60 days of this year in my 2018 Tax return. It’s just for $125, I’m I obligated to claim it?

You can use them on a future income tax return but you need to first report them on the 2018 tax return and carry them forward.  In order to do this, you will need to submit an adjustment request for the 2018 income tax return.  Please see the following FAQ for instructions on how to file an adjustment request.

https://turbotax.community.intuit.ca/replies/2647992