I also think it's a warning.
However for me to even have a guess at it what it could mean, I would need to have a bit more info.....such as.... Does it always happen or is it only on certain sites?. What Browser are you using and, if you do you have a virus protection programme in your computer, what is it? etc.
As much info as possible is required for a Techie to offer an explanation and I am not a Techie but, sometimes, come -up with an idea from an Internet search or, more likely, from what I have read in AB.
Ron.
Ron.