Love your Scottie
what a sweet little old guy
I would say,definitely have any lumps checked out,one of my cats(from many years ago) who was overweight had a small lump,my then vet said it was a fatty lump.
A few months later it was large and cancerous,the vet was wrong and at the time I was too ignorant,poor Peppi had to be put down.
I have learned my lesson.
So yes,always be vigilant with lumps and bumps..