I'm having my roof redone as we speak and I noticed the roofer is installing ice and water shield under the drip edge. I thought it was supposed to be installed over the top of the drip edge? Everything I've found online indicates installing TWS over the drip edge. I questioned it and he said that under the drip edge was correct and they were going to install another strip over the drip edge before shingling. Is this OK or should I press the issue?