I don't think you need to worry abou it. My landing paper is Imm5292, also having a stample of "Not valid for travle" on it.
I drove my car through Lewiston(Niagara Falls) via I-190, the customer officer didn't ask many questions, I just told him I am landed PR redident and wanted to enter Canada, I have my landing paper on my passport, he just let me in.
If you still have some questions, eamil me at glalong@hotmail.com.
