Growling/Hissing - Very unexpectedly

I am new here. We have 3 male cats. One is 1 1/2 years old. The other two are brothers and just over 1 year old. Besides the initial week of them getting used to each other over a year ago, all three kitties have had absolutely no problems getting along. They all play together, lick each other, and live well together. They are all indoor cats. Today we were working outside and they sat at the windows watching us. We came in and vaccuumed which Tivo (one of the brothers) always gets really, really scared of. A few hours after all this, we heard Tivo growl then hiss at Baxter (the oldest) as BAxter walked near him. Baxter barely even looked up, and it did not seem to affect him. Any time Tivo gets near BAxter he growls or hisses. I have never heard him do this before. He is always the lazy, quiet one. Tivo did not attack at all. Baxter doesn't really even notice. Burton (the other brother) is completely fine with both cats. Tivo seems completely normal besides this. Still playing with toys...Still cuddly and nice to us.

DOES ANYONE HAVE ANY IDEAS FOR US???? What are some thoughts....
Thank you all so much!!!

i wouldn't worry. it sounds like tivo and baxter had a minor "tiff" while you were outside. this was probably over "dominance" and it sounds like baxter won. the reason could be as simple as tivo was crowding baxter in the window while they were watching you outside. i have three male cats and it's like clockwork that something will happen every month or so and all of a sudden for a few days or a week two of them will act like they hate each other. just give it a little time and they will probably work it out and be back to being "best friends" again. no need to intervene.

feral65 is probably right, even human best friends and family fight. He'll get over it soon enough!