Yes, I would say Gus was aware of Mike for a while. I believe it will be revealed that Nacho is actually working for Gus, as a "spy", or at the very least is doing business with Gus on the side, since we know that Mike used Nacho's extracurricular drug dealing as leverage over him previously.

@Drew007 said:

It seems like Gus was onto Mike all along, even prior to Mike going to kill Hector. It makes me wonder if he had Mike under surveillance when he was meeting with Nacho or after his fight with Tuco. It seems like he really caught his attention after he hijacked Hector's truck. It also didn't help that Mike sent Jimmy to trail a mark in the restaurant. I think after Jimmy, Gus knew that Mike, even though he didn't know who he was at the time, was onto him and eventually find out who Gus was.

Which would make sense why Nacho only gave Mike a warning during their meeting. (I was wondering why Nacho reacted the way he did.) He didn't want to reveal that he worked for Gus but he wanted to warn Mike to not cause too much trouble with Hector.

@LadyGigi said:

@Drew007 said:

It seems like Gus was onto Mike all along, even prior to Mike going to kill Hector. It makes me wonder if he had Mike under surveillance when he was meeting with Nacho or after his fight with Tuco. It seems like he really caught his attention after he hijacked Hector's truck. It also didn't help that Mike sent Jimmy to trail a mark in the restaurant. I think after Jimmy, Gus knew that Mike, even though he didn't know who he was at the time, was onto him and eventually find out who Gus was.

Which would make sense why Nacho only gave Mike a warning during their meeting. (I was wondering why Nacho reacted the way he did.) He didn't want to reveal that he worked for Gus but he wanted to warn Mike to not cause too much trouble with Hector.

Yes totally agree.