Depends, you can have a love for people in general that isn't defined by them specifically... basically you love because you believe in love or whatever and it's more to do with you. So... if it's in that context i could understand it and doesn't bother me.
However, if it's like we're best friends and i love you based on the other person after 3-4 days that's a bit much. I realize time relativity is much different in the Big Brother house where a week can be like a month but the first 3-4 days just seems preemptive to me in that context.