Tenant smelling cigarette smoke in neighbor's apt how to handle?

[Axia Roberts]

I have an apartment complex, 8 units. I had one tenant move into Apt G 2 months ago and then the other moved into Apt F about a week ago. Apt G is a single older woman, and Apt F is a younger couple. I have had no complaints from any other tenants about the new tenants. Apt G claims that she smelled cigarettes and it was so bad it was seeping into her apt and she has health problems. So, since Apt F was new, a few days ago I just casually reminded them where they can smoke if they happen to be smokers. They both don't smoke, and I already knew that as I asked before they signed the lease. They have never smelled of cigarettes when I've spoken to them, and that smell tends to linger. So, I told Apt G that I had spoken to the new tenants and she thanked me. Well, later on, Apt G starts texting me about it again so I told her I'd look into it. Apt F was having issues with their lock and they couldn't be at the apt, so I let the locksmith in. Perfect chance to see if anyone is smoking in there, and I step into the entrance of the apt, and I smell nothing. There is absolutely no evidence of smoking of any kind in that apt. Not even incense or an over powering air freshener. I'm not a smoker, but doesn't the smell linger, even if you cover it up? They're 1 bedroom 1 bath 800 square foot units. The smell would be everywhere, right? So, I just told Apt G all of that and I'm waiting for her reply. My question is, how do I handle this? Both tenants are good, but Apt G is becoming a bit of a bother to me. I actually just offered to let her break her lease as she was only short term anyway (here while her home is being repaired, it was damaged in the hurricane) and it's getting to the point where she texts me almost nightly to  tell me about the smoking that I'm not seeing any evidence of. If she doesn't want to move out, what should I do? Or say to her? And I forgot to mention, there is a no smoking clause in their leases and the building has always been smoke free. Have I done everything I need to do? I just want to be sure I'm handling this correctly and I certainly don't want to bother Apt F if they're not breaking their lease. I haven't told Apt F that Apt G thinks they're smoking because I don't want them to be uncomfortable.