It should just meant your oestrogen level is increasing. In a natural cycle you get an oestrogen peak just before the LH peak, which is then followed by O. That's why you get EWCM just before you O. On a stim cycle your oestregen levels will usually be high (but not "peaking").

You only need to worry if you get the LH surge, which can be detected by the b/t your Dr does or opks. The LH surge is part of what the synarel is suppressing.