I'm finding input--> output and salt has more to do with my weight loss than anything else. And by that I mean literally what goes in and what comes out of you. If you're not eating enough fiber to push everything else out you may not notice losses as much and notice weird trends. Also plateauing really, really sucks.
How do your clothes feel? How much do you weigh now? Caloric intake? Making sure that intake is REALLY the right intake? (No matter how much I count if I order/takeout food I gain weight - period. I try not to eat out anymore, I don't go to dinner get togethers because I just can't seem to get an accurate count).
At 100-130 miles a week if you're keeping up a decent balanced diet you might be putting some muscle on which won't show up on a scale. What kind of effort do you do when you're riding? Do you use a heart monitor?
Also you may just be plateauing and have to mix up the cycling - some sprints along with longer rides.
HOWEVER - 5 pounds a month is STILL 5 pounds a month in the right direction. The harder you are on yourself about a positive trend of loss the more likely you'll get really fed up and reach for the cheeseburger and undo what you have.