This is true and false at the same time. FOREX is not single sourced
from any single exchange as there is no exchange. Forex prices are basically
pulled from world banks, this means the prices will never "tally" from
one supplier to another, unless they are drawing from say a single
Something that may LOOK behind may actually be in front, it is just the way the the prices fall in that instant.
It is important that you focus on the wider angle to this. IF you start
to mentally drill down to individual prices this will cause problems
with your trading for sure. Keep that wider picture in focus all the time.