The vague concept of "tiny Transformers" was around, even if it wasn't mentioned in Prime. Fixit showed up in RiD right after Prime, so it's safe to say the idea of there being tiny robots was something likely to cross the minds of people working on the show.
I mean, I'm no-prizing, but I think it makes sense. Why was the armor able to adjust to Miko? It had been designed to work for anyone that could fit in it, and the diversity of Transformer bodies meant that it had to be DAMN good at adapting to different occupants.
And yes, Bulky would tear a hole in spacetime to see Miko again. Especially after RiD, there's no good reason for him not to.