I don't know, we had some unidentified Haze strain going around western MA. It was a BEAUTIFUL plant with big, pale green buds- not giant colas, but the kind of big nugs that look SO good in a baggie. She took a while to finish- your probably will too; hazes are notoriously slowpokey- I think I ran her 10 weeks but it was the same deal, I got the seeds labeled only 'Haze' from a grower friend and no other info.
The reason you think yours is small for 4 weeks probably has a lot to do with the type of plant. It might just be getting off to a slow start. IF it takes 9 or 10 weeks to finish, expect it to pack on some sERIOUS weight within the last 3 weeks.
At this point, you are going for HEALTHY. The hardest part about growing a long-flower strain is keeping the damn thing happy for 2 1/2 months, lol!